PowerShell "Advance" parsing to calculate components installation time based on log file

Question

Hi,

i have an application that create a log file of the following format:

2009-03-27 15:30:50 Start
2009-03-27 15:30:51 Starting Component 1 Installation
2009-03-27 15:30:52 blah
2009-03-27 15:30:53 blah
2009-03-27 15:30:54 blah
2009-03-27 15:30:55 ~~~ Finished Component 1 Installation ~~~
2009-03-27 15:30:56 Starting Component 2 Installation
2009-03-27 15:30:57 blah
2009-03-27 15:30:58 blah
2009-03-27 15:30:59 blah
2009-03-27 15:30:60 ~~~ Finished Component 2 Installation ~~~
2009-03-27 15:30:61 Starting Component 3 Installation
2009-03-27 15:30:62 blah
2009-03-27 15:30:63 blah
2009-03-27 15:30:64 blah
2009-03-27 15:30:65 ~~~ Finished Component 3 Installation ~~~
2009-03-27 15:30:66 Finished

I guess you get the point of the format.

The thing that i want to achive is to have a powershell script that will return a table of result showing

1. Component Name
2. Start Time
3. End Time
4. Time Taken

I call it "advance" script because it will probably include: parsing, formatting, creating of new objects, etc

• I am a newbie in powershell

Answer 1

The following script might do that for you ... IF you resort to sensible time values ... more than 60 seconds in a minute are weird (and gave me a few exceptions here that caused major headaches over the date/time parsing, until I noticed why the exceptions were thrown ...)

$logfile = $args[0]

$log = get-content $logfile

$Components = @()

switch -regex ($log) {
    "(.*) Starting (.*) Installation" {
        $c = New-Object PSObject
        $st = [DateTime]::ParseExact($Matches[1], "yyyy'-'MM'-'dd HH':'mm':'ss", $null)
        $c | Add-Member -Type NoteProperty -Name Component -Value $Matches[2]
        $c | Add-Member -Type NoteProperty -Name StartTime -Value $st
    }
    "(.*) ~~~ Finished" {
        $et = [DateTime]::ParseExact($Matches[1], "yyyy'-'MM'-'dd HH':'mm':'ss", $null)
        $c | Add-Member -Type NoteProperty -Name EndTime -Value $et
        $c | Add-Member -Type NoteProperty -Name TimeTaken -Value ($c.EndTime - $c.StartTime)
        $Components += $c
    }
}

$Components

I could get the execution time down a bit (by about 25 percent) with the following code:

$logfile = $args[0]

foreach ($l in Get-Content $logfile) {
    if ($l.Length -ge 30) {
        if ($l.Substring(20,8) -eq "Starting") {
            $c = New-Object PSObject
            $st = [DateTime]::ParseExact($l.Substring(0,19), "yyyy'-'MM'-'dd HH':'mm':'ss", $null)
            $c | Add-Member -Type NoteProperty -Name Component -Value $l.Substring(29, $l.Length - 42)
            $c | Add-Member -Type NoteProperty -Name StartTime -Value $st
        } elseif ($l.Substring(24,8) -eq "Finished") {
            $et = [DateTime]::ParseExact($l.Substring(0,19), "yyyy'-'MM'-'dd HH':'mm':'ss", $null)
            $c | Add-Member -Type NoteProperty -Name EndTime -Value $et
            $c | Add-Member -Type NoteProperty -Name TimeTaken -Value ($c.EndTime - $c.StartTime)
            $c
        }
    }
}

but I find it much less readable (let alone maintainable) than the first solution. That's very rigidly linked to the layout of the log file.